I don't agree. The doll is probably a fabrication pulled out of thin air to allow her to leave the school compounds while adding a little "cuteness" to the mix. Rather than character development, there'll probably development of more chibi Sayo avatars and signatures instead. If Sayo's gonna get character development, it can only happen in school and through her story of how she died and became a ghost.

Then consider this Parrywinkle. Ken is going thru all the trouble inventing a way for Sayo to join Negi's crusade and that she probably has the best affinity with Zazie (potentially an important character later on) being a ghost and Zazie a medium of sorts. Sayo could be the potential key in dealing with Zazie within Negi's crew and her own supernatural being could also bridge a connection to the 'other-worldly' creatures Negi's is most likely to meet.

-I wonder if a pactio can be made to a ghost or any non-human being, that would be so cool and potentially plot expanding.

Then consider this Parrywinkle. Ken is going thru all the trouble inventing a way for Sayo to join Negi's crusade and that she probably has the best affinity with Zazie (potentially an important character later on) being a ghost and Zazie a medium of sorts. Sayo could be the potential key in dealing with Zazie within Negi's crew and her own supernatural being could also bridge a connection to the 'other-worldly' creatures Negi's is most likely to meet.

-I wonder if a pactio can be made to a ghost or any non-human being, that would be so cool and potentially plot expanding.

yeah but we dont know if zazie is even going. she wasnt on the plane or anything, or at the airport

Then consider this Parrywinkle. Ken is going thru all the trouble inventing a way for Sayo to join Negi's crusade and that she probably has the best affinity with Zazie (potentially an important character later on) being a ghost and Zazie a medium of sorts. Sayo could be the potential key in dealing with Zazie within Negi's crew and her own supernatural being could also bridge a connection to the 'other-worldly' creatures Negi's is most likely to meet.

-I wonder if a pactio can be made to a ghost or any non-human being, that would be so cool and potentially plot expanding.

A valid argument.

Perhaps there are ghosts or spirits to be found in Magic World as well.